The present invention relates to a resin-sealed chip stack type semiconductor device in which chips are mounted one above the other thereby eliminating a space between the chips and thus realizing a dense arrangement of the chips in the device.
FIG. 5 shows a cross-section of the conventional resin-sealed ball grided array (BGA) type of semiconductor device. Legend 11 represents a ball and there are a plurality of them. Legend 12 represents a substrate placed on the balls 11. Legend 13 represents a chip (hereafter, first chip) mounted on the substrate 12. Legend 14 represents a chip (hereafter, second chip) mounted above the first chip 13. Legend 13a and 14a are the wires that connect the first chip 13 and the second chip 14. Legend 15 represents a sealing resin which covers and protects anything and everything arranged above the substrate 12. Filler is mixed into this sealing resin in order to enhance the thermal conductivity of the sealing resin. Thus, the conventional resin-sealed BGA type semiconductor device has a structure in which two or more chips of different sizes are stacked one above the other and the chips are incorporated in one package.
However, when the chips are stacked in this manner, there arises a problem that a short-circuit occurs between the wire 13a of the first chip 13 and the second chip 14. Similarly, there arises a problem that a short-circuit occurs between the wire 13a of the first chip 13 and the wire 14a of the second chip 14. In addition, there has been a problem that the filler mixed into the sealing resin forcefully penetrates in between the first chip 13 and the second chip 14 and damages the chips.
It is an object of this invention to obtain a resin-sealed chip stack type semiconductor device that can avoid a short-circuit between the wires and the chips, between wires, and prevent the damage of the chips due to penetration of the filler which is mixed into the sealing resin.
The resin-sealed chip stack type semiconductor device according to the present invention comprises a substrate placed on many balls, a bottom chip to which wires are connected, a top chip to which wires are connected and mounted above the bottom chip, a non-conductive bonding layer which functions to bond and fix the two chips to each other, and a sealing resin which covers and protects all the components mounted on the substrate. The non-conductive bonding layer is provided by die bonding in such a manner that is at least covers the portion of the bottom chip where the corresponding wires are connected and does not allow generation of a gap between the two chips.
Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings.